[ONNX] Sum empty tensor could not be exported to ONNX successfully. (#58141) (#59537)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59537
PyTorch sum over empty tensor gives 0, while ONNX produces an error.
torch.sum will be translated into onnx::ReduceSum op. Per the definition of ReduceSum, update the keepdims attribute for this scenario.
Test Plan: Imported from OSS
Reviewed By: nikithamalgifb, ansley
Differential Revision: D29046604
Pulled By: SplitInfinity
fbshipit-source-id: 6f5f3a66cb8eda8b5114b8474dda6fcdbae73469
Co-authored-by: fatcat-z <jiz@microsoft.com>
